Hindu nationalist Narendra Modi is set to become India's next prime minister, four major exit polls show.

The early results suggest his opposition party, and its allies, are likely to sweep to a parliamentary majority in the world's biggest ever election.

A Bharatiya Janata Party (BJP) candidate, Mr Modi electrified the lengthy contest with a media-savvy campaign that hinged on vows to kickstart India's economy and create jobs.

Yet much depends on Mr Modi winning enough seats to form a stable government that can push through promised reforms.

Elections are notoriously hard to call, and polls taken before and after voting have a patchy track record.

Results of the ballot are due to be announced on Friday.

A majority of 272 seats in parliament is needed to form a government, although that is often achieved with outside support from regional parties.

The BJP-led alliance is forecast to win 270-282 seats, according to a poll conducted by research group CSDS for the CNN-IBN television network.

Congress faces humiliation

Forecasts predict 92-102 seats will go to the coalition led by the Congress party, which would be worst ever result for the ruling party led by the Nehru-Gandhi dynasty.

Congress spearheaded India's independence movement and has governed the country for over 50 years since freedom from British rule in 1947.

If the BJP and its pre-election allies can win an outright majority, it will be the best showing by a single group since Congress and its allies won 414 seats in 1984 - when the assassination of then-prime minister Indira Gandhi created a swell of public sympathy for the party.

Several national exit polls over-estimated the BJP's seat share in the last two general elections in 2004 and 2009.

The Congress party went on to form coalition governments on both occasions.

"We will only know if this 'Modi wave' has really happened after the election results," said Praveen Rai, a political analyst at CSDS who recently published a report on exit polls.

"It still might be more of a media wave, a manufactured wave."

Mr Raji said Uttar Pradesh -- India's most populous state, and a crucial political battleground -- is particularly tricky for pollsters to forecast because it is a caste-sensitive state where some voters are afraid to speak frankly about who they chose.

Another poll released on Monday, by Nielsen for ABP News, showed the BJP-led alliance hitting 281 seats.

A third, by Cicero for the India Today group, predicted Modi's alliance would take between 261 and 283 seats, and pollster C-Voter forecast a tally of 289.

One outlier poll, by Today's Chanakya, showed the BJP emerging with enough seats to rule on its own.

Modi denies role in religious riots

A Modi victory would be a blow for campaigners who have long maintained he is an autocratic Hindu supremacist, responsible for an outbreak of religious riots in his home state, Gujarat, in 2002.

In the clashes more than 1,000 people, mostly Muslims, died.

Mr Modi, who rose from humble roots as a tea vendor's son, was shunned by Western nations for years after the bloodshed in Gujarat, where he has been chief minister since 2001.

However, his rise on the national stage forced a rethink among the European Union and the United States, whose ambassadors have met him to patch up relations.

Mr Modi denies the accusations against him and a Supreme Court inquiry found no evidence to prosecute him.

India's voting was spread over five weeks to reach the country's 815 million voters.

Moscow's words and actions — including the alleged poisoning of a former spy — are not the results of random aggression but rather fall into distinct patterns that can help us anticipate Russia's next moves under Vladimir Putin.